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Discussion Starter · #1 ·
Hi, I am hoping that regulars at ClubWRX can help me diagnose the infamous controversial deceleration noise. Sorry to make yet another thread about it, but the other ones are older and I was curious if this issue has been resolved. I have an Exedy stage 2 clutch with 36k on it, and I just installed the TiC rear diff mount bushings w/ outrigger bushings (comfort). I started to notice a scraping noise which has grown almost unbearable, strictly under deceleration while in gear (if I disengage the clutch this does not happen either). While I did notice an increase in NVH with the bushings in, I did not think it would be this bad. It sounds like it is coming from the rear of the car, but I am not entirely sure. Anyone with a similar problem or one who resolved the issue? Input greatly appreciated, thanks!
 

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Discussion Starter · #2 ·
I also forgot to mention that I found a shards of metal on the plug of the rear differential when I was draining the fluid. I'm not too sure if this can be what is causing the noise because I thought defective differentials whine, and not just under deceleration?
 

· Not a mod... or is he? Or, is he not?
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If the fluid has never ever been changed you'll find them as the diff wears in. A failed diff can make all sorts of noises. From whines to a chattering noise. You can also hear a clunk when going from forward to reverse as the mesh has too much play.

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Of course hard for us hacks to tell, but if you have shards of metal in the diff case, I'd bet that is the problem. And gears whine/make noise whenever the teeth do not match up good enough. It depends on how bad the mismatch is whether they whine, scrape, grind, etc. The 'whine' generally comes when they are not so bad yet as to scrape or grind. It is the vibration of the gears hitting a natural resonant frequency. I think something has caused your rear diff gear teeth to wear........
 

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Discussion Starter · #5 · (Edited)
If the fluid has never ever been changed you'll find them as the diff wears in. A failed diff can make all sorts of noises. From whines to a chattering noise. You can also hear a clunk when going from forward to reverse as the mesh has too much play.

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So you're saying that it is possible the new fluid could just be setting in? A transmission expert told me the diff should be ok for a while as long as the car isn't launched, etc. To clarify, I hear no noise other than a loud scraping while decelerating (coasting) in high RPMs (noise only occurs with 0% throttle applied and is dampened by braking). Could this be a clutch related problem? It is a heavier than stock clutch...
 

· Not a mod... or is he? Or, is he not?
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No, I'm saying if you have a vehicle that has the factory gear oil in it that it isn't uncommon to find a small amount of shavings. If you have had it changed before or recently I would perhaps consider having the diffs inspected.

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Discussion Starter · #8 ·
I think I finally traced the source of the noise to the installation of the rear differential bushings and outrigger bushings multiplying the resonance caused by drivetrain shock. Hope this helps anyone else with the same issue.
 
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